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First time accepted submitter drichan writes "Those of us who watched the live feed of last night's Falcon 9 launch could be forgiven for assuming that everything went according to plan. All the reports that came through over the audio were heavy on the word "nominal," and the craft successfully entered an orbit that has it on schedule to dock with the International Space Station on Wednesday. But over night, SpaceX released a slow-motion video of what they're calling an 'anomaly.'"

Libertarians rode the back of this and shouted about how much better it would be to privatise space. But in fact we're just right (*) here again, with SpaceX substituted for Boeing.

I think you'll find it's not just libertarians cheering for this - after all, privatizing the launch infrastructure has been a key element of Obama's space plans. The difference from the previous situation, where NASA relied on bloated defense contractors, is that SpaceX and its competitors will have to enter fixed-price bids, instead of the old cost-plus contracts which gave the contractors zero incentive for efficiency. Whether this will actually work in the long run remains to be seen, but it's hard to see how this is worse than the old system, and putting the federal government into the launch vehicle business sounds like a spectacularly awful idea.

I don't think you know how these so-called fixed-price bids work for governments. They're not fixed at all as the contract or language implies. They are just starting points for negotiations on more contracts as the scopes and costs change on both ends of the contract.

Basically a government fixed-price request is a very vague description of an idea. The fixed-price bid is a very vague description of a project and associated budget. Whether or not the budget then balloons to eclipse the specified price is irrelevant to the bureaucracy on either side.

That's not consistent with what I've read about this subject. For instance: [nss.org]

...in some quarters outright disbelief remains regarding the launch prices actually posted on the SpaceX website for the Falcon Heavy. No other company has posted fixed launch prices on the Internet — only SpaceX. The actual taxpayer cost of US government launches can only be guessed by calculating from the cost-plus contract costs, which are usually for multiple launches from the same customer. If SpaceX does multiple launches, the posted price would be reduced depending on the number of launches.

Rather than the traditional cost-plus model, in which companies are reimbursed the cost of a project plus an additional amount that guarantees them a profit, SpaceX and Orbital are working under newly established Space Act Agreements, in which NASA pays increments of a fixed price once the companies accomplish previously agreed upon milestones.

To reiterate, this is no guarantee that it will actually work better (and not just more cheaply) than the old system. For it to really be a success there needs to be a competitive market, a sustainable business model, and a lack of heavily subsidized competition from the Chinese. But I really hope it does succeed.

The reason why you can have a fixed price contract in this situation is that NASA isn't really defining any requirements; also not changing them midstream; but also that there is little development risk. The rocket from SpaceX isn't really anything innovative, which is actually a good thing, not a bad thing.

Where fixed price contracts don't work is when you have a significant amount of development risk, and you end up having to build that into the cost of the contract, meaning that you often don't end up with low price bids. Europe's ESA for example pretty much only works from Fixed Price contracts, which builds in the cost of that risk into the project, inflating the bid cost, and you end up with Europe overall, not really committing to many projects, because they get sticker shock.

I like the unintentional "it's far worse than you think" vibe I get off this description.

Basically a government fixed-price request is a very vague description of an idea. The fixed-price bid is a very vague description of a project and associated budget. Whether or not the budget then balloons to eclipse the specified price is irrelevant to the bureaucracy on either side.

The more profit the private side gets, then the more money for bureaucracies on either side either directly through profit or indirectly through bribes and the revolving door. Such things are illegal only if you get caught. This is a built in incentive to balloon costs of projects.

To clairfy the contracts that SpaceX and Orbital are operating under for station resupply are neither "cost-plus" nor "fixed price" contracts, they are "fee for service" contracts. NASA pays for certain miletones successfully achieved and cargo delivered to the station. NASA doesn't buy Falcon 9's or Dragons (the Dragon remains the property of SpaceX) they are buying the service (just as they buy FedEx and Airline tickets)

First of all, US government solicitations can be vague or specific. When they are vague, it is intentional in order to encourage a wide variety of proposals. Have a look at: http://www.sbir.gov/solicitations [sbir.gov]

Now here is where you are very wrong. Bids and proposals are anything but "a very vague description of a project and associated budget". Maybe years ago, in some areas of the US Government this was true. Maybe its still true in a handful of areas. But right the majority of DoD propos

Weren't all rockets built by private companies? So why not let private companies compete against NASA (which is now mostly just a wealth-transfer entity - subsidizing US corporations)

Now that it's been demonstrated that space can be cheaper then what NASA is used to doing, other companies can get in on the game. So NASA will be able to have some options in the selection of their manufacturers.

What I don't like is the fact that space is becoming increasingly privatised.

Why? All it really means is that launch costs are getting low enough that it no longer requires the resources of a nation-state to do them. Historically, that has marked the tipping point where money starts pouring in and advancements accelerate. So why not let SpaceX's investors pay for further research into the matter? It's not like it excludes anyone else from doing likewise.

The Falcon 9, as its name implies, has nine engines, and is designed to go to orbit if one of them fails. On-board computers will detect engine failure, cut the fuel supply, and then distribute the unused propellant to the remaining engines, allowing them to burn longer. This seems to be the case where that was required, and the computers came through. The engines are also built with protection to limit the damage in cases where a neighboring engine explodes, which appears to be the case here.

Obviously SpaceX wants to achieve man-rating so that they can launch and return personnel in addition to the cargo runs they're currently beginning. I'm curious as to how this moderate malfunction will impact the rest of the program.

Bearing in mind, of course, the deaths of Chaffee, Grissom, and White in the Apollo 1 accident, the launch-time engine failure and later unrelated catastrophic failure for Apollo 13, the Challenger disaster, and the Columbia disaster, it's difficult to call SpaceX's anomaly as being any worse than those. If SpaceX manages a series of cargo deliveries without any loss of the capsule or with complete success on delivery then even with this anomaly they're arguably no worse off than any of the previous space programs were, as far as reliability and safety goes.

Obviously SpaceX wants to achieve man-rating so that they can launch and return personnel in addition to the cargo runs they're currently beginning. I'm curious as to how this moderate malfunction will impact the rest of the program.

Bearing in mind, of course, the deaths of Chaffee, Grissom, and White in the Apollo 1 accident, the launch-time engine failure and later unrelated catastrophic failure for Apollo 13, the Challenger disaster, and the Columbia disaster, it's difficult to call SpaceX's anomaly as being any worse than those. If SpaceX manages a series of cargo deliveries without any loss of the capsule or with complete success on delivery then even with this anomaly they're arguably no worse off than any of the previous space programs were, as far as reliability and safety goes.

The important thing is whether they can successfully determine what actually happened, and why it happened (i.e. replicate the malfunction on a test bed engine). This was the thing Feynman was most critical of NASA for post-Challenger - that the whole disaster was caused by this faulty assumption about engineering risks on the O-Ring seals (i.e. the seals were getting eroded by exhaust during launch, but the question posed was "is this dangerous" not "why is this happening" - the former being foolish since the system was not designed to cope with this, and it's true cause was unknown).

It's a triumph that the launch still succeeded, but having averted an unforeseen consequence the only safe thing to do is make sure it's both forseen and mitigated in the future.

Very true, especially in the infancy of SpaceX's program. I do hope that they figure out why the engine failed, and hopefully their records on its manufacture and testing prior to its use will contribute toward answering that.

I'll have to ask my wife about it- she actually is a rocket scientist, albeit one that deals with solid rockets, not liquid, but I'd expect that the post-failure analysis would follow the same kinds of procedures.

No it was a known glass transition temperature problem - the o-rings were not safe to use below a known temperature. It's the sort of problem where you can soak a squeaky rubber toy in liquid nitrogen for a while, then pull it out and shatter it with a hammer.

Surprisingly, if failure is measured in terms of human deaths, fairly high failure rates are tolerable in many branches of engineering. It was assumed that about 5 people would die in the construction of a tall sky scraper. Now, with massive changes in safety, it is possible to build a sky scraper with no deaths. However, injuries still happen.

Similarly, mining regularly kills people. They have reduced their deaths per year from several thousand (1907) to averaging 6/year (2001-2005). See government re [msha.gov]

The Ars Technica article states that Apollo missions had the same protections against engine failure, and that two of the Apollo missions actually suffered engine losses and still completed the mission. So, maybe there's precedent?

Yep, you can't have all the answers until you know the questions. Components of the lift vehicle may have failed, but the failsafes performed as designed and the mission was completed successfully and on schedule. The redundancies and backups are built in as a function of the design, and may not even be called into action most of the time. All in all, this is proof that the system works, and I can not wait to see more launches. This was a perfect result and demonstrates a functional system that is good and will get even better.

If you took a team with an average age of 23 to the World Series or World Cup finals, you wouldn't complain if they only won 3-2.

The first outage was during an earlier Apollo with a dummy payload - they actually failed to achieve their planned orbit and had it been a moon launch, they would have had to scrub. But since it was just a test, and since they thought they knew the solution - they called it a success and did not delay the program.

No, the engine did not explode. The fairing around the nozzle was crush by the sudden loss of interior pressure when the engine shut down -- the external pressure was then much higher than the nozzle's interior pressure (no more rocket exhaust) and it got crushed and fell away, harming nothing. The engine is still there, intact, and it did, in fact, just turn off.

If that's accurate, then SpaceX is looking into a shutdown event, a LOT different than a destructive failure. The fairing imploding will either be the anticipated result, or a new issue to understand and resolve/document.

Shutdown may be accompanied by data, and there is a fix. Valves, pumps, all kinds of fairly well understood stuff to analyze and resolve. Destructive catastrophic failure would be much more disturbing.

So far, they seem to be doing at least as well as NASA did in the early days. Mercury was a real crap shoot, and early Saturn development was exciting to say the least. I filled a few scrapbooks with notes on those faiures. Fun times...

So much can get forgotten from one generation of engineers to another -- especially all the things that did not work. Even assuming all the information is publicly available, the effort spent collecting it, organizing it, and filtering it from a vast amount of other information at the time is potentially valuable.

Re-read their reply. It didn't explode (they still received telemetry from the engine).The debris seemed to be something else, maybe a small part being the engine, but the engine as a whole is more or less fine.

Actually, according to SpaceX engineers, it did not explode as they were able to continue to communicate with it. The current theory is the outer covering blew off because of the change in pressure.

From TFA:
"We know the engine did not explode, because we continued to receive data from it. Our review indicates that the fairing that protects the engine from aerodynamic loads ruptured due to the engine pressure release, and that none of Falcon 9’s other eight engines were impacted by this event."

I don't think it's the fact that there was a failure, or the fact that the system proved resilient, it's the manner in which the failure manifested itself - an engine cutout, a fuel pump failure, or a vibration issue would be cause for a post launch investigation and a pat on the back, while a wholesale engine disintegration will trigger quite a significant inquiry and a heck of a lot of furrowed brows.

It's the difference in magnitude of failure which is the thing to note here.

As the update to the article from SpaceX points out - the engine didn't blow.

Approximately one minute and 19 seconds into last night’s launch, the Falcon 9 rocket detected an anomaly on one first stage engine. Initial data suggests that one of the rocket’s nine Merlin engines, Engine 1, lost pressure suddenly and an engine shutdown command was issued immediately. We know the engine did not explode, because we continued to receive data from it. Our review indicates that the fairing that protects the engine from aerodynamic loads ruptured due to the engine pressure release, and that none of Falcon 9’s other eight engines were impacted by this event.

As designed, the flight computer then recomputed a new ascent profile in real time to ensure Dragon’s entry into orbit for subsequent rendezvous and berthing with the ISS. This was achieved, and there was no effect on Dragon or the cargo resupply mission.

Falcon 9 did exactly what it was designed to do. Like the Saturn V, which experienced engine loss on two flights, Falcon 9 is designed to handle an engine out situation and still complete its mission.

As designed, the flight computer then recomputed a new ascent profile in real time to ensure Dragon’s entry into orbit for subsequent rendezvous and berthing with the ISS. This was achieved, and there was no effect on Dragon or the cargo resupply mission.

IIRC, there was no way to recompute a Saturn 5 flight profile on the fly. Remember, kids, that was back in the days when we hunted dinosaurs from the backs of our '57 Chevys. Kudos to SpaceX for having enough out of the box thinking to have the needed software routines in the can already and ready to go. Falcon 9 is more than just another Big Dumb Booster, AAMOF, from everything I'm reading and seeing of its operation, it's pretty goddamned smart. Remember the test flight to the ISS? The first launch attempt, the onboard computers detected a glitch that might have taken out the bird and shut down and aborted the launch right at T -0, even after the humans tapped the buttons authorising the computers to do the launch. Like I say, some serious onboard smarts programmed by some seriously smart people.

The computer was fitted to the instrument unit (IU) that was on the S-IVB stage. That computer controlled the stack up until the stage (S-IVB) fitted with the instrument unit was jettisoned. (There abouts anyway, I'm sure there was a "hand-off" to the Apollo guidance computer). Technically the earliest of Saturns had no IU, but they were not manned flights. I believe this was due to the IU still being in development. Here is more on the IU:

The Saturn V used a pitch and roll program early in the launch, then switched to closed-loop guidance. If I remember correctly, the digital computer calculated the ideal orientation to reach the desired orbit and an analogue computer tried to move the operational engines to achieve that. So the capability was limited, but it was there.

From what can be read between the lines, the engine didn't explode but rather imploded. It shut off at "maximum dynamic pressure", sometimes called simply "Max-Q", when the atmospheric pressure pushing against the vehicle due to its velocity is at the highest it can be at that point in the flight. Between the pressure from outside of the spacecraft and from the nearby engines, the nozzle apparently collapsed in on itself and tore loose, hence the debris.

The engine itself was still there, just missing the nozzle. That is why data was continuing to be sent from the engine and respond to system queries about its status. Had it exploded, those sensors and microcontrollers running the engine would not be in place.

Technically you are correct that all that could be said from the telemetry is that the sensors were still in place, but those sensors would not be registering if it was an outright explosion.

It wasn't an engine explosion, the protective fairing around the engine shattered when the engine cutoff caused a major change in pressure. SpaceX said that they continued to receive telemetry data from the engine which means it did not explode, and in fact was physically intact though not functioning correctly.

They've launched 4 Falcon 9 rockets. One engine has failed, so that's an observed failure rate of 1/36 or about 3%. The means the odds of 0 or 1 engine failing (a successful launch) is 97.6% and the odds of more than one failing is 2.4% assuming the currently observed rate is representative of the actual rate. 2.4% would be an excellent failure rate for any rocket launch system. In fact, no one has achieved a failure rate that low. And bear in mind this rate includes 3 experimental launches and only one production launch. Of course, a launch failure can be brought about by more than just engine failures, so 2.4% is really a minimum and other factors which haven't yet manifested themselves would add to it.

Space X is saying that this is probably a failure in the aerodynamic structure of the rocket, not the rocket engine itself. If that's the case, the above statistical analysis is invalid because it assumes no interdependency in engine failures. A structural failure could lead to more than one engine failing. It would also be problematic in assessing the future failure rate because the engine configuration is going to change in their 1.1 version. The outer engines will be circularly arranged in future versions while in current versions they're arranged in a square.

...The means the odds of 0 or 1 engine failing (a successful launch) is 97.6% and the odds of more than one failing is 2.4% assuming the currently observed rate is representative of the actual rate. 2.4% would be an excellent failure rate for any rocket launch system. In fact, no one has achieved a failure rate that low....

There are vehicles that have matched or beaten this rate. The Delta 2 (retired) achieved 149 out of 151 (99%). The currently active Soyuz-U has achieved a failure rate indistinguishable from this (741 successes out of 761, 97.4%). There are other vehicles that claim 100%, but have launched too few to be able to claim this rate. One factor to consider is that launch systems often mature and have a long series on unbroken successes after having some failures early on: http://www.spacelaunchreport.com/log2012. [spacelaunchreport.com]

No, this is not a correct analysis. You have to break it up into all 512 possible outcomes and then calculate the probability for each. So one of the possibilities is that all engines will work, that has a probability of (35/36)^9 or 77.6%. There are 9 possible ways that one engine could fail. Each possibility has a probability of (1/36)^1*(35/36)^8 or 2.2%. If you multiply that by the 9 single engine failure possibilities you get a probability of 20.0% that exactly one engine will fail. So if a successful

Fourth, what's the value in the US having a launch system of its own without depending on other countries?

Fifth, what's the likelihood that having this launch system prove to be successful will result in the developer working on heavier-lift systems?

When the United States has no launch system we are completely dependent on the Russians for access to a very expensive machine built with enormous cost to us and to all of the other participating countries. Should the Russians decide that they don't want to play anymore, they could simply deny our astronauts access, making the station de facto Russian property. Since the Russians have significantly more station experience than we do, I'm sure that they'd be able to operate it without us.

Our having a launch system, ultimately intended to be man-rated, essentially prohibits that possibility. Same with the Europeans, if they ever have a man-rated rocket. I'm all for that.

Let's see, there was the Titan IV which took out a facility at Edwards AFB on April Fools Day in 1991. [nytimes.com] Now that was an Air Force engine, but fairly modern. There was another Titan IV which exploded in more spectacular fashion. [nytimes.com]

Then there's the Delta II, which is a newer launch system which has exploded at least twice that I'm aware of. Once in 1995 [youtube.com] and another in 1997 [nasa.gov].

The point is that NASA and the Air Force and their various subcontractors, SpaceX not included, don't have a perfect record on launch vehicle malfunctions. You can't have lots of propellant with oxidizer burning without some sort of malfunction. While still rare, these events can and do happen and it's good to see SpaceX plan for these kinds of things unlike the Soviets did when their Moon Rocket went "boom" when they were testing in the 60s [youtube.com] In Fact, all four launches of the N-1 were failures. [starbase1.co.uk]

The interesting thing is what may be a failure of the orbital insertion of the Orbcom satellite that was supposed to use the 2nd stage of the Falcon 9 for an additional burn after separation of the Dragon. Apparently either due to this engine loss of the 1st stage or some other problem, that satellite didn't get to the desired orbit.

It will be interesting to see if SpaceX will refund Orbcom their money or do something extra to help them out.

If the ascent vector isn't correct, (which it wasn't, due to the failure), then the entry vector for the capsule will be different from the one planned. This is the likely cause of the orbcom deployment snafu.

It's basic geometry. The angle changed, so the insertion point changed. (The tangent intersection of the satelite orbit relative to the ascent vector) That's why the sat isn't in the proper place.

There was nothing wrong with the insertion. The Falcon 9 actually shuts down two engines [nspo.org.tw] during late flight of the first stage so as to not exceed 5g acceleration anyway. The reason the sat didn't get into it's proper orbit is because they weren't permitted to perform the required re-igniting of the second-stage after sending Dragon on it's merry way due to rules placed upon them by NASA and co. the first-stage engine out (see above for links).

Actually there was nothing preventing the Orbcom sat from being inserted into the proper orbit but for rules by NASA and their ISS partners (Russians) that told them that they were not allowed to reignite the second stage [orbcomm.com] because of the malfunction in the first stage.

I think that highly depends on whether there's any more engine failures on the next flights. If it seems like an odd case and SpaceX can say that "and even such a thing were to happen again, we'd catch it" then all is well. If another one fails and it smells more like "our engines aren't exactly 100% reliable, but we're betting on statistics that two of them won't fail on the same flight" then that's not good.

I'd hold off on speculation until after forensic evaluation of the failed component (if it doesn't burn up in re-entry), and failure data sent from the vehicle. All we know for sure is that the safety kicked in, and the engine shut down.

I don't have access to the falcon 9's engineering data, so I can't comment definitively; take with copious salt.

A rocket engine is basically a fuel supply line coming from some fuel tanks, being injected under pressure into the reaction chamber, nestled inside the burn cone.

A failsafe system would clamp down fuel and oxidizer supplies at multiple points along the supply to ensure that neither reaches the reaction vessel in the event of a flow, pressure, or reaction anomaly. Such systems would need to be ver

No, failsafes refer to a designed-in failure method that is not catastrophic to the whole assembly.

Some engines, like turboshaft engines, have an intentional narrow point in the driveshaft designed to fail under the right circumstances. If something's got to give, make it something that fails without either destroying the machine outright or else killing the occupants.

A rocket design that manages to avoid destroying the vehicle when an engine explodes definitely qualifies as fail-safe.

Not to take anything away from SpaceX, but to the extent that you mean to suggest "SpaceX did a better job than NASA did early on" (which may be none at all), it's of course not really fair to compare considering that SpaceX didn't exactly throw out the knowledge that NASA and others built up because of those failures.

TFA only tells half the story. MSNBC [nbcnews.com] has more. Dragon is fine, but it's possible that the launch's secondary objective, which was to put the first of an 18-satellite telecom array into a tricky high-inclination orbit, went a little screwy as well, and the sat isn't in the proper orbit at the moment. Details are still being dug out.

Apparently the second stage didn't hit the required orbit for NASA to allow them to restart it without risk of collision with ISS if something went wrong. So it looks like SpaceX could have restarted the stage but NASA didn't let them; it was a consequence of the first stage engine failure, not a second failure.

Failure to reach the orbit that SpaceX claimed that they were going to put the satellite into is to me massive egg on the face of SpaceX and will make it harder to sell future flights unless they can provide some assurance that even the secondary payloads will be able to meet mission objectives.

Except it appears that the only reason for the 'failure to reach orbit' was that NASA said they couldn't restart the engine due to the possibility of hitting ISS if something went wrong. That only applies to flights to ISS, not to satellite launches.

– Both Saturn V and the shuttle launch system were designed to handle failure of at least one engine
– The entire engine didn't actually explode, as some sources have reported; the onboard computers were still sending data from it (SpaceX believes it was just the aerodynamic casing (fairing) that exploded, due to the pressure release of the engine)
– This doesn't mean the Falcon 9 system is necessarily less safe than NASA systems; on two occasions, Saturn V rockets experienced a similar loss, with similar (i.e., nil) impact to the mission's success

So, y'know. Rejoice nerdily about the fact that the failsafes worked, rather than worrying about commercial technology being inferior.

The shuttle can get to orbit with just two of the liquid fueled engines, but was designed to return with just one. Turns out, you can deorbit a shuttle with just the maneuvering jets.

Unfortunately, a failure of the solid fueled boosters, is mostly fatal.

I'm thinking that's because the orbiter was bolted onto the side of the launch vehicle. I'm thinking, if it would have been mounted on top like a normal capsule, it probably wouldn't have killed that crew. But hey, IANARS, so my opinion means shit.

I'm thinking that's because the orbiter was bolted onto the side of the launch vehicle.

To a large extent it's because it had wings. If you need wings to land and they fall off, you die.

Surviving a launch accident in a winged rocket is very hard, because you have to get from flying vertically to flying horizontally at supersonic speed without anything falling off. Normally the best you can do is fit ejection seats and cross your fingers as you pull the handle.

The X-20 with an escape rocket below the spacecraft was probably the closest to being survivable and the tests for that looked pretty ha

I read this in the official statement too - I'm guessing it makes perfect sense to rocket scientists.

My best guestimate: because of the sudden lack of exhaust gasses from the engine, the pressure inside the fairing changed extremely significantly and quickly, and the fairing couldn't take the pressure delta, so it ripped apart.

For the first stage, one at launch, two later on. From a strict physics perspective, you could probably have three or four out in the last few seconds of the burn, but I don't know if their software is that clever. The second stage has only one engine.

Did anyone here a call of engine cut-off in the NASA TV feed? I did not. Or a call for a longer burn? Seems the SpaceX team would have made those calls. Of course, they could have on private channels. Seems NASA was more transparent.
Also, when I fly I like my pilots to be well dressed and professional. The SpaceX team did not. Maybe that is the SpaceX culture, but I am an old fart and I prefer a much more orderly look.

I missed the launch, and I haven't been able to find a recorded feed: if anyone has a link I'd love to hear the flight loop.

BUT, the mission control chatter you hear on a SpaceX launch is almost entirely people assuring themselves that the rocket is OK. They're not *controlling* much of anything: it's all in the hands of the flight computer, which decides things like "shut down this engine and recompute a launch profile for the remaining 8 engines" on its own, in real time. There's no time for humans to m

I was not trying to say they would have had to do any manual intervention, and I would fully exept them to NOT have to, just like what happened last night. But as you mentioned, it did not appear like they noticed. Anyhow, I am glad the SpaceX engineering effort paid of. Good job.

Did anyone here a call of engine cut-off in the NASA TV feed? I did not. Or a call for a longer burn? Seems the SpaceX team would have made those calls.

The decision to shut down engine #1 and the decision to adjust the other engines' burns to compensate were made automatically by the flight-control computer onboard the rocket. There's no need for the ground team to make the decisions, and no need for the computer to make voice announcements about them.

Your points are well taken, but in reviewing the NASA feed, the voice-over clearly stated that "all nine Merlin engines... continue to burn..." after 2 minutes. I believe this was a NASA voice-over, so that may be where the discrepancy happened. As for your analogy, I agree, but given today's techno-crap most cars are coming with, it would not surprise me if this does not happen in the near future, say for low breake fluid or cylinder misses.

Apollo 6 lost two engines and, AFAIR, suffered partial breakup of the SLA panels covering the lunar module due to pogo.Apollo 13 lost one engine, which was fortunate because pogo had grown so bad that the Saturn V was on the verge of structural failure. If the engine hadn't failed, they'd have been parachuting back to Earth soon after.